Comment by trogdor | Hacker News Reader

Comment by trogdor | Hacker News Reader

The highlights, as I understand them:

-In November 2022, the principal investigator on this study published the results of a different study which found MRI evidence of ACL healing in 30% of patients who were randomized to physical therapy with optional delayed ACL reconstruction. [0]

-When an ACL is fully torn, the gap between the ruptured ends inhibits healing. Since the ruptured ends are in closest proximity at 90°-135° of knee flexion, this study investigated whether bracing the knee at 90° would facilitate ACL healing.

-This study lasted five years and involved 80 patients. All participants had full-thickness ACL tears (complete discontinuity of the ACL on MRI). The protocol involved four weeks of bracing the knee at 90°, followed by progressive brace adjustments that slowly increased knee range of motion. The brace was removed at 12 weeks.

-At three months, 90% of patients showed evidence of ACL healing on MRI. Moreover, MRI evidence of ACL healing was associated with better outcomes.

This is monumental.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9872245/

So 90% of patients who wore the knee brace instead of getting a surgery healed properly?

There is no definition of “healed properly” in relation to ACLs, in part because it is (hopefully soon was) commonly believed that a ruptured ACL has limited healing capacity.

Patients were eligible for this study if they presented within one month of acute ACL rupture confirmed on MRI. The MRI had to show full discontinuity of ACL fibers.

“After management with the Cross Bracing Protocol, 72 out of 80 (90%) participants with complete discontinuity of the ACL at baseline had signs of ACL healing (ACL continuity) on 3-month MRI.”

The paper explains the rating scale they used to evaluate ACL healing on MRI.

Thanks for the closer reading!

They didn't heal, a full rupture is a full rupture.

They showed that for younger patients they can, through physical therapy, replace the ACL stability function with overcompensated proprioception and musculature.

I wonder what the outcome of this would be as patients get older and start to lose muscle mass.

I had a tear sometime in the 90s, and then not surgery until the 2000s, the good old cut your kneecap in half kind.

The doctor I saw once a year prior seemed to imply this. He implored me to do specific weight exercises, and claimed if I did it right 'you wont even need that surgery.' So it must have been at least a working theory for a while?

They did heal.

> After management with the Cross Bracing Protocol (CBP), 72 out of 80 (90%) participants with complete discontinuity of the ACL at baseline had signs of ACL healing (ACL continuity) on 3-month MRI.

Seems pretty definitive as healing to me.

Huge for reducing unnecessary surgical procedures. In what situations would surgery still be required?

Edit: would imaging be able to delineate?

Having 10% not heal isn’t great… Since surgery is much more reliable I see it still being standard of care.

How reliable is surgery?

Surgery is invasive and recovery is rough. Not sure what the data says but I would’ve liked this option

Standard of care could be bracing followed by surgery if it's not taking.

No, 90% is massive if true. Speaking from experience the surgery is an absolutely brutal experience. Even though my graft was successful, if I had my time over I'm very much not sure I would make the same choice. I would at least explore other avenues. Many people do fine without an ACL. In my case my cartilage went from, in my surgeons words, pristine (post injury and before surgery), to tricompartmental osteoarthritis 18 months after the operation.

Surgery involves taking strength from another ligament (and attached muscle group) and a long and painful recovery process.

Not to mention costs tens of thousands of dollars.

Surgery is expensive and ACL tears are not "critical." Showstopper for basketball, soccer, etc, but not for walking, squatting, running, etc

(I've had a re-torn ACL for ~8 months now. I'll get surgery eventually.)

You have to remember that surgery comes with very significant secondary risks (MRSA infection, etc, etc).

Last I heard, Dr. Filbay is working on a decision aid for patients.

Here’s my guess as to what it’ll suggest:

First, do the bracing protocol. Then do intensive physical therapy. If, after both of the above, you have functional instability that is adversely impacting your quality of life, consider surgery. Otherwise, don’t.

>Would imaging be able to delineate?

Seems like a strong maybe. Check out “Implications of findings” on page 7 of the paper.

The only thing that's tough about this approach is you work hard at physical therapy but still you end up being the percentage that still needs surgery. Then once you get surgery you have to start all over again. I delayed ACLR personally because of a multi ligament tear and the toughest part was the burnout of starting back up again after surgery.

I had a so-called terrible triad (MCL/ACL/meniscus) so in addition to ACL reconstruction, my surgery included meniscus debridement. I unequivocally needed surgery (it was a contact injury playing sports), and thanks to surgery made a 100% recovery (albeit with a ton of PT!). That said, if surgery can be avoided in less traumatic tears (e.g., "stop-and-pop" ACL tears) so much the better!

Just had my ACL reconstructed out of my quad a few weeks ago, and the thought of just being in a brace rather than harvesting my quad tendon sounds lovely!

Monumental especially for football players who are usually never the same after an ACL surgery which often leads to the shortening of the tendon, limiting its efficacy and putting it at a greater strain which leads to an inevitable relapse.

I’d think for athletes a 10% chance of failure would make it a total non starter.

This is an odd take. From what I understand from the article it’s a 90% chance of healing, after which you can still get surgery — which doesn’t heal but restores some functionality by grafting from another tendon. I’d imagine athletes would be particularly interested in trying this new treatment prior to considering surgery.

My assumption was that the original comment was about professional athletes. For them any delay to returning is generally considered disastrous, and reconstruction success rates for them are near 100%, their recovery timelines are extremely quick, and doing PT all day isn’t really that different from what they normally do. Recovered performance is also incredibly good these days in most cases.

This conservative approach could become the default for most everyone else, but for professional athletes 90% success is not going to fly.

If the original comment was about casual athletes then none of this applies.

The patients were 26+-10 years, so possibly less applicable later in life, but still fantastic

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